Star minded
Flutes, squeaks, clicks and whistles - the Stare's musical repertoire proves to be extremely versatile every year. But the songbirds have even more in store: the art of grammar.
Exactly forty years ago, Washoe dared to question the uniqueness of human beings. The young female chimpanzee learned sign language from her teachers, Beatrix and Allen Gardner, in 1966 and was even able to create new word combinations. So it was clear: Animals also have at least a basic understanding of language.
But language is more than stringing together words; it is also characterized by grammatical rules. As the American linguist Noam Chomsky recognized back in 1957, this means that an infinite number of sentences can be formed from a finite number of words.
Recursiveness is an important grammatical principle: Linguistic elements can be built into sentence structures as often as you like without violating the grammar. So the sentence "Oedipus ruled Thebes" can be supplemented by: "Oedipus, who killed his father, ruled Thebes." The game of these insertions can be continued at will: "Oedipus, who killed his father, whom he met in the street, ruled Thebes." Linguistically not nice, but grammatically correct.
Chomsky saw this as a typical human quality that is innate and, as a universal grammar, makes it possible for every child to learn their mother tongue. The chimpanzee Washoe could sign simple sentences, but she couldn't handle complicated box constructions.
The cotton-top tamarin (Saguinus oedipus), who is also gifted in languages, also showed little understanding of grammar: the animals failed miserably in 2004 when the two psychologists Tecumseh Fitch and Marc Hauser tried to teach them recursive rules. Does man remain unique in the high art of grammar?
What apes can't do, songbirds might do, thought Timothy Gentner and his colleagues at the University of Chicago. The researchers chose the European starling (Sturnus vulgaris) as the language learner, whose ability to learn is well known. After all, the songbird knows how to keep expanding its musical repertoire by imitating other bird calls or noises, so that a varied creaking, crunching, squeaking, smacking, clicking and whistling sound can be heard.
The researchers now combined two typical Star elements – a rather rattling noise and a trilling whistle – into sentence structures. These either followed a rather simple grammar according to the rule (AB), in which a sentence AB can only be lengthened at the beginning or at the end to AB-AB. Or the grammar worked recursively according to the rule AB; that is, insertions like A-AB-B were allowed.
The researchers tried to teach these grammar rules to eleven starlings by training them for months. The birds should peck a button whenever they heard a recursive song, but keep their beaks still when hearing the simpler version. Each correct choice was rewarded with a treat.
Starlings are smarter than we think
(Daniel Margoliash) Nine of the eleven starlings passed the grammar test. They also recognized the recursive structure in combinations of up to four different rattles and trills that they had not heard before.
This blurs the line between human and animal language talent. "As we can see, there is also a star on our side of the border," emphasizes co-author Daniel Margoliash, adding: "Starlings are smarter than we think. We should no longer insult them as 'sparrow brains'."
But why can songbirds do something that our primate relatives can't? "One intriguing possibility," says New York University psychologist Gary Marcus, "is that only species that can acquire new vocalization patterns -- like songbirds, humans, and perhaps some whales -- have the ability to recognize recursiveness. " Chimpanzees like Washoe lack this ability. While monkey grammar therefore remains limited, songbirds such as starlings show a much more sensitive sense of language.
